d0(cm) di(cm)  1/d0  1/di  h0(cm)   hi(cm)    |m|     dm 
------ ------  ----  ----  -----   -------   -----  ------
50     12.5                4.04    1.0
45     12.8                4.04    1.2
40     13.0                4.04    1.3
35     14.2                4.04    1.6
30     15.1                4.04    2.0
25     17.6                4.04    2.8